Intermittent fasting
concept · updated
Eating within a compressed daily window (or occasionally skipping longer) is a low-cost way to pull the hormesis lever: it lowers mTOR, raises AMPK, and triggers autophagy — the body’s cleanup of damaged tissue.
Why it may work
- When the stomach is empty, the body is freer to digest waste tissue (autophagy) instead of processing incoming food (Longevity).
- Calorie restriction is a stressor that appears to slow aging — the same AMPK/adversity mechanism as cold and exercise (Sinclair).
- Ketosis: the two easy routes into it are restricting carbs or fasting; mitochondria run more efficiently on ketones than glucose (Head Strong).
Common protocols on file
- 16:8 — Sinclair fasts ~16 hours, drinks hot water/coffee/tea through it, eats nuts if he must (Sinclair).
- The 12–8pm window — Karpathy’s time-restricted eating; the practical default (Food).
- One meal a day (OMAD) — Jack Dorsey frames it as a “boring superpower” for mental clarity; three meals is a social structure, not a biological requirement (Jack Dorsey).
- Longer fasts (a day+, not beyond a week to avoid muscle loss) — deep autophagy after ~3 days; the liver learns to regulate glucose after ~3 weeks of practice (Sinclair).
Caveats
- Muscle is the priority — don’t fast your way into losing it (see strength training); longer fasts risk muscle loss.
- Most of the aggressive claims come from Sinclair’s contested framework (supplements). Time-restricted eating is the low-risk core; extended fasting is more experimental.
Related
Citations
- Lifespan (Talk at Google) — David Sinclair
- Critique of Sinclair’s longevity claims — Charles Brenner
- Biohacking Lite — Andrej Karpathy
- Head Strong — Dave Asprey
- Longevity FAQ — Laura Deming
tags: health longevity fasting nutrition